CO2 competes with radioactive chemicals for freshwater recovery: Hydrate-based desalination

Sol Geo Lim; Chang Yeop Oh; Sun Ha Kim; Kongtae Ra; Ji-Ho Yoon

doi:10.1016/j.jhazmat.2023.132812

CO₂ competes with radioactive chemicals for freshwater recovery: Hydrate-based desalination

J Hazard Mater. 2024 Jan 15:462:132812. doi: 10.1016/j.jhazmat.2023.132812. Epub 2023 Oct 20.

Authors

Sol Geo Lim¹, Chang Yeop Oh¹, Sun Ha Kim², Kongtae Ra³, Ji-Ho Yoon⁴

Affiliations

¹ Department of Convergence Study on Ocean Science and Technology, Ocean Science and Technology (OST) School, Korea Maritime and Ocean University, Busan 49112, South Korea.
² Western Seoul Center, Korea Basic Science Institute (KBSI), Seoul 03759, South Korea.
³ Marine Environmental Research Center, Korea Institute of Ocean Science and Technology (KIOST), Busan 49111, South Korea.
⁴ Department of Convergence Study on Ocean Science and Technology, Ocean Science and Technology (OST) School, Korea Maritime and Ocean University, Busan 49112, South Korea; Department of Energy and Resources Engineering, Korea Maritime and Ocean University, Busan 49112, South Korea. Electronic address: jhyoon@kmou.ac.kr.

PMID: 37879276
DOI: 10.1016/j.jhazmat.2023.132812

Abstract

Here, we introduce CO₂ hydrate-based desalination (CHBD) technology for freshwater recovery from radioactive wastewater, for water particularly containing Cs and Sr. The hydrate equilibrium curves of CO₂ hydrates shift towards lower temperature and higher pressure regions as the concentrations of CsCl and SrCl₂ increase. X-ray diffraction and Raman spectroscopy measurements found that neither CsCl nor SrCl₂ can affect the structure of CO₂ hydrates. The high-pressure micro-differential scanning calorimetric results demonstrate that CO₂ hydrates in the presence of CsCl and SrCl₂ started to dissociate at lower temperatures due to the enrichment of CsCl and SrCl₂ in the remaining solutions. The formation kinetics results indicate that increases in the concentrations of the radioactive chemicals lead to a decrease in the initial reaction rate and sub-cooling temperature. Solid-state nuclear magnetic resonance spectroscopy was utilized to confirm the exclusion of radioactive isotopes from solid gas hydrates. Importantly, the CHBD technology proposed in this study is applicable to radioactive wastewater containing Cs⁺ and Sr²⁺ across broad concentration ranges, spanning from a percent to hundreds of parts per million (ppm), and even sub-ppm levels, with comparable recovery efficiency. This study presents new insights into the potential of environmentally sustainable technologies to overcome the challenges posed by radioactive wastewater.

Keywords: Carbon dioxide; Desalination; Dissociation enthalpy; Gas hydrate; Radioactive wastewater.